Dental handpieces (and similar power-operated hand tools) having electric lamps for illuminating work areas are well known. Because of the small dimensions of such handpieces, particularly near their working ends, the usual practice is to mount such a lamp within the handle of the handpiece or within a threaded connector that joins the handpiece to the hose for supplying drive air and water. Such a construction is disclosed in coowned U.S. Pat. No. 4,600,384. Other U.S. Pat. Nos. revealing the state of the art are 4,330,274, 4,398,885, 4,375,964, 4,777,252, 4,334,863, and 4,514,169.
While such systems have been generally effective in operation, common disadvantages relate to the problems of lamp replacement. Ordinarily, disassembly of a number of parts is required to gain access for lamp removal and replacement. Even when such access is gained, the tiny lamps may be difficult to grasp for extraction and insertion. Sometimes lamp-containing modules must be removed and then either the lamps must be separated from the modules or the entire modules must be replaced. In the latter case, the difficulties of replacement may be reduced but only at the expense of substantially greater replacement costs.
Accordingly, a main aspect of this invention lies in providing a lamp-containing connector assembly and a lamp extraction/insertion tool which greatly simplify the task of lamp replacement while keeping to a minimum the time and cost involvements in such an operation. To remove a lamp, a dentist (or other operator) need only detach the handpiece from the connector and insert the head and stem portions of the tool into an exhaust air passage extending through the connector body. The exhaust air passage extends alongside the socket that contains the lamp and communicates with that socket through a slot or window that extends substantially the full length of the socket. The base portion of the lamp is provided with a lug that projects radially outwardly through the slot and into the exhaust air passage. Therefore, by the simple operation of fully inserting the head and stem portions of the tool into the exhaust air passage, then shifting the head laterally and withdrawing the tool, the lug may be easily engaged by the head portion and the lamp extracted from its socket as the tool is withdrawn.
In addition to providing access for lamp engagement and removal, the elongated slot slidably receives the lug in a way that orients the lamp so that proper mating engagement of electrical contacts is made when the lamp is fully inserted. Of particular importance is the fact that the slot also functions to allow cooling exhaust air to flow laterally from the exhaust air passage into the socket for cooling the bulb during operation. The heat absorbed by the air is then conducted away from the bulb through exhaust air passages or ports in the connector body.
In terms of structure, the connector body is generally cylindrical with a longitudinally-extending lamp-receiving socket and an exhaust air passage extending longitudinally through the body and alongside the socket. The exhaust air passage and socket communicate with each other through a narrow slot extending substantially the full length of the socket. A lamp received in the socket has bulb and base portions with the latter being provided with integral, radially-extending lug means dimensioned to extend transversely through the slot into the exhaust air passage and to be slidable along the slot during bulb insertion and extraction.
The lamp is generally cylindrical in configuration and has a diameter sufficiently smaller than the socket to provide an air flow space about the lamp when it is fully inserted. In addition, the connector body has an end wall defining at least one outflow passage at the base of the socket and a restricted exhaust port at the end of the exhaust air passage. The restriction in the exhaust air passage, the spacing about the lamp, and the outflow passage(s) at the base of the socket all contribute to insuring the circulation of cooling air about the lamp and the discharge of such air after being heated by the bulb.
The insertion/extraction tool has an elongated stem portion terminating at one end in a handle portion and at its opposite end in an enlarged head portion. The head portion is generally cylindrical and its diameter is smaller than the clearance space in the exhaust air passage between the end of the lug protruding into that passage and the wall of the passage directly opposite from the slot. Since the lug is spaced from the extreme end of the base portion of the lamp by a distance greater than the axial dimension of the head portion of the tool, the lug may be easily "hooked" by the head portion for extraction of the lamp from its socket. The combined length of the stem and head portions may be substantially the same, and in any event no less than, the distance between the face of the connector body and the restricted port near the distal end of the exhaust air passage, and the handle portion of the tool is preferably larger in cross section than the exhaust air passage. At the end of the tool opposite from the head portion, a stub portion may be provided having substantially the same diameter as that of the lamp, such stub being useful for seating the lamp in its socket.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.